Accuracy of RDT-based diagnosis of malaria in patients in rural and urban areas in the Ashanti Region of Ghana By Mutala Abdul-Hakim (MPhil Microbiology )

STRUCTURE OF PRESENTATION INTRODUCTION MATERIALS AND METHODS RESULTS/DISCUSSION CONCLUSION

INTRODUCTION Malaria is one of the most prevalent infectious diseases worldwide. In 2017, a total of 219 million cases of malaria were recorded, an increase of 2 million cases over the previous year.1 Persons at greatest risk for severe illness or death from malaria include low socioeconomic individuals or people living in rural areas that lack access to healthcare.2 1. WHO (2018). World Malaria report; 2. Igbal et al., (2016). Journal of Tropical Pediatrics

INTRODUCTION CONT’D According to the WHO, all suspected cases of malaria should be tested before treatment. RDT offers great potential to address this need. However, RDT also has its technical and operational challenges as the persistence of the parasite protein (HRP-2) detected by RDT, as well as concerns over the possible deletion of the hrp2 gene may yield false positive or false negative results. This study therefore seeks to assess the accuracy of HRP-II- based RDT used in hospitals using microscopy as the “gold standard”.

MATERIALS AND METHODS Study area Figure 1: Map showing the various study areas

MATERIALS AND METHODS CONT’D Study Participants The study targeted patients accessing healthcare at the aforementioned facilities. Exclusion criteria Patients who were critically ill and those dissenting to give their consent were exempted from the study. Ethical issues Ethical clearance was sought from the Committee on Human Research, Publication and Ethics of the KNUST, School of Medical Sciences and Komfo Anokye Teaching Hospital.

MATERIALS AND METHODS CONT’D 304 Blood samples Structured questionnaire administered after consenting community hospitals Agona (AGH) Kuntanase (KGH) Kumasi (KSH) Microscopy RDT Slides stained with 10% Giemsa Quantity by counting 200 or 500 WBC

RESULTS Figure 2. Mean age of participants Figure 1: Age distribution of participants Figure 2. Mean age of participants

RESULTS CONT’D Out of the total sample size, there were 30 (9.8%) verified malaria cases by microscopy and 34 (11.2%) verified malaria cases by RDT Figure 3: Number of RDT and microscopy positive cases in each community

RESULTS CONT’D Sensitivity (%) Specificity (%) NPV (%) PPV (%) KSH Using Microscopy as the gold standard the sensitivity, specificity, NPV and PPV was calculated Table: 1 Accuracy of HRP-2-based RDT in each community Sensitivity (%) Specificity (%) NPV (%) PPV (%) KSH 55.5 93.4 95.5 45.4 AGH 80.0 95.3 75.0 96.4 KGH 83.3 95.9 71.4 99.0 Total 72.9 94.9 80.8 80.2 NPV = Negative Predictive Value, PPV = Positive Predictive Value

RESULTS CONT’D Sensitivity (%) Specificity (%) NPV (%) PPV (%) Kumasi Table 2: Accuracy of HRP2-based RDT (parasite density ≤100 parasite/µl of blood) Sensitivity (%) Specificity (%) NPV (%) PPV (%) Kumasi 50.0 93.0 94.0 45.0 Agona 67.0 95.0 60.0 Kuntanase 75.0 97.9 99.0 NPV = negative predictive value, PPV = positive predictive value

RESULTS CONT’D AGH had the highest parasite density (mean = 99.53) followed by KGH (mean = 66.77) with KSH (60.29) having the lowest parasite density Figure 4: Parasite densities of infected samples across the three sampling sites

CONCLUSION RDT used in the three communities had varying levels of accuracy (low sensitivity but relatively higher specificity). The sensitivity of HRP-2-based RDT is highly dependent on parasite density. The overall sensitivity was relatively low and below the WHO standard of ≥ 95%. It is therefore important to assess the accuracy of RDT to improve upon its quality.

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